Green thoughts: Bully in the bog

By David Chinery

Wednesday, November 28, 2012

You don't have to be a canoeist, hiker, or birdwatcher to know phragmites. This is one of those "55 M.P.H." plants, easily identified in roadside wetlands as you speed by in your car. Unfortunately, once you get to know phragmites, you probably won't like it.

Phragmites, pronounced "frag-my-tees," is also called common reed and is known scientifically as Phragmites australis. It is a tall plant, sometimes reaching over 15 feet, and can live in fresh or brackish water in a variety of situations - along streams or rivers, in pond or marshes. It can also thrive on dry land. Long, flat leaves of medium green are topped by a plume-like flower cluster at the top of the plant. Stout rhizomes, which can grow both horizontally and vertically, allow the plant to thrive and spread, and the roots have been known to penetrate mud down to six feet or more. Once it has colonized a neighborhood, phragmites means to stay.

Tragically, it crowds out other vegetation, provides little food for wildlife, and forms such a dense stand that wildlife moves elsewhere. In short order, the ecological community turns into a phragmites ghetto. Check out the roadsides of I-787, the banks of the Mohawk River, and Route 9J south of Rensselaer, to name just a few such sites.

For many years, researchers puzzled over the identity of phragmites: introduced thug or native gone bad? It's found in many other parts of the world, including Europe and Asia, but an analysis of peat cores in North American wetlands proves that phragmites was here at least 3,000 years ago as well. The next hypothesis was that wetland disturbance, dredging, pollution, and other man-induced changes caused native phragmites to become much more common, and then a problem. However, these same changes were found to cause phragmites populations to decline in Europe. The best answer to the riddle is the discovery that various ecotypes of phragmites exist in different parts of the world. These ecotypes look virtually the same, but may grow differently and have subtle genetic and physical differences. Apparently, native American ecotypes behaved well and lived with other plants in mixed plant communities. Early in the 19th century, a European ecotype was introduced here, and these plants have become rampant, invasive pests, crowding out even the native phragmites. Today, the European and North American phragmites are considered two distinct subspecies. The lesson: even though a collection of plants may all look the same on the outside, they might differ tremendously in their growth habits.

What can property owners who find phragmites growing in their midst do? Several control options have been used, including controlled burning, grazing, dredging, herbicides, flooding, or lowering water levels. No method is a "magic bullet." Biological control using a variety of native and imported insects which might eat phragmites to death are being studied. Hopefully, researchers will come up with a plan that reduce populations of this rambunctious character and allows animals and other plants to enjoy more diverse wetland habitats.

David Chinery is an educational director at Cornell Cooperative Extension of Rensselaer County. Write to him at dch3@cornell.edu